A number of chemicals (e.g. ethanol, butanol and succinic acid) can be made from cellulosic material in a process which involves hydrolysis of the cellulosic material to obtain mono- and di-saccharaides followed by biological conversion of the saccharides to the target chemical.
In the hydrolysis step, enzymes or mineral acids may be employed for hydrolysing the polysaccharides of the cellulose. In order for such polysaccharides to become more accessible to the hydrolytic agents, the cellulosic material may be pre-treated. Pre-treatment is particularly important when the cellulosic material is lignocellulosic material, because the lignin of the lignocellulose protects the cellulosic polysaccharides from the hydrolytic activity.
Various pre-treatments have been described in the prior art. Steam explosion, wet oxidation and ammonia fiber explosion (AFEX pre-treatment) are some proposed variants. Alkali treatment is another (see e.g. WO09025547 and U.S. Pat. No. 5,693,296 A). A number of pre-treatments based on milder acidic conditions have also been suggested.
Further, different methods based on mechanical treatment of the cellulosic material have been described.